Conventional centrifugal pumps include an impeller that rotates within a cavity in the body of the pump. Fluid entering from an inlet in the cavity typically flows toward the impeller and near to the impeller's center of its rotation. Further, the rotation of the impeller typically forces fluid to flow radially outward toward an outlet of the cavity that is often at a location that is radially adjacent to the impeller.
Producing high head output by centrifugal pumps often requires that the impeller be rotated at accelerated speeds. However, such accelerated speeds are typically associated with the generation of a relatively significant shearing force that is applied to the fluid that is flowing through the pump. Yet such shearing forces may be unacceptable for at least certain types of fluids and/or solids that are passing through the pump. For example, food processing systems, pharmaceutical processing systems, and clay slurries, are examples of applications in which a high shearing force may be unacceptable due to the potential damage that such shearing forces may cause to the structure of the fluid and/or the solids within the fluid. Thus, in applications in which the fluid or solids flowing through the pump should not be subjected to such shearing forces, typically the impeller may be operated at a low pump speed and have a low head output. Moreover, to avoid and/or minimize the generation of such shearing forces, the total head generation capability of the centrifugal pumps may be limited or centrifugal pumps may not be used in such applications.
Additionally, low shear centrifugal pump designs, particularly food grade pumps, have relatively lower efficiencies than standard industrial centrifugal pumps. Thus, low shear centrifugal pump designs often result in pumps that have more internal recirculation of fluids and/or solids within the pump and have higher power requirements.